Introduction 2,3-Dichloro-5,6-dicyano-1,4-benzoquinone (DDQ)
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is a powerful oxidizing agent and has proved to be versatile reagent for various organic transformations. Apart from its well-known applications as a dehydrogenating and oxidizing agent, in recent years it has found number of other applications in synthetic chemistry, including deprotection of various functional groups, cleavage of linker molecules from solid support, introduction of unsaturation and C-C, C-O and C-N bond-formation reactions. In recent years, it has shown wide potential for oxidative cyclization leading to a variety of heterocyclic ring skeletons such as benzopyrans, xanthenes, alkylindans, benzoxazoles, and oxazolidinones. It has found application in steroid chemistry and in the synthesis of complex natural products,
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where its unique regioselective properties gave excellent results for the preparation of key intermediates. DDQ was also found to be an excellent reagent to cleave methoxybenzyl ethers
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and an efficient catalyst for the alcoholysis of epoxides
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as well as for the hydrolysis of acetals.
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DDQ is commercially available and its first synthesis was described by Thiele and Gunther in 1906. It can be prepared by a six-step procedure involving cyanation and chlorination of benzoquinone.
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